Face mask ventilation, or bag-valve-mask ventilation, is a routine procedure which allows for oxygenation and ventilation of patients by ensuring proper airway patency. Effective mask ventilation has two requirements. First, airway patency must be established. Second, leakage between the patient's face and the mask must be eliminated.
Difficult mask ventilation, which often results from an inadequate seal between the patient's face and the mask, poses significant challenges, particularly to anesthesiologists. The patient's safety hinges upon proper ventilation and oxygenation during anesthesia. Recent studies have found an approximately 5-8% incidence of difficult mask ventilation. Various predictors of difficult mask ventilation include patients that have a thick or obese neck, edentulous dentition, facial hair, sleep apnea, and those patients that snore or are obese. Particular facial features can also result in difficult mask ventilation, including a prominent nose, a narrow facial structure, and hollow cheeks.
Another important consideration regarding mask ventilation is its effect on the clinician performing the procedure. When prolonged mask ventilation is required, the clinician's hand that holds the mask can tire easily for two reasons. First, the hand must apply increased pressure on the mask in order to achieve a tight seal. An additional pair of hands may be required to press the mask against the patient's face to facilitate ventilation. Second, the mask has an abnormal shape that the clinician's hand must conform to in order to establish a reliable and steady grip. These factors which lead to fatigue can be exacerbated by the predictors of difficult mask ventilation as described above. Additionally, clinicians with small hands have to work harder to achieve adequate seal and ventilation. This can be attributed to the distance between the thumb, which sits on the dome of the mask, and the little finger, which rests on the posterior angle of the patient's mandible. Improving the mask structure in order to achieve a tight seal with less effort allows anesthesiologists to focus more on maintaining airway patency. This ultimately will result in better mask ventilation and a decreased risk to patients' safety during anesthesia.
Adapting masks to facilitate a better seal is generally known, as shown in WO 97/07847 which discloses an anesthesia mask with finger grips which protrude from the dome of the mask and guide the placement of the thumb and index finger. U.S. Pat. No. 6,651,661 discloses an anesthesia mask that is ergonomically defined with a left/right asymmetrical design that accommodates holding the mask to the patient's face with the left hand.